The several objectives of this research include studies of the cell-free biosynthesis of the oral antibiotics griseofulvin, tetracycline and pencillin, and the 13C-labeled study of the biosynthesis and structure of the anti-tumor antibiotic hedamycin. Another objective is the development of models for polyketide biosynthesis including tetracycline and aflatoxin as ultimate target molecules. A new theory for penicillin and cephalosporin biosynthesis will be tested via laboratory model studies. This work will lead to a deepening of our understanding of the biosynthetic pathway for many classes of natural product structures.